BS EN ISO
14555:2006
BRITISH STANDARD
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Welding — Arc stud
welding of metallic
materials
The European Standard EN ISO 14555:2006 has the status of a
British Standard
ICS 25.160.10
12&23<,1*:,7+287%6,3(50,66,21(;&(37$63(50,77('%<&23<5,*+7/$:
BS EN ISO 14555:2006
National foreword
This British Standard was published by BSI. It is the UK implementation of
EN ISO 14555:2006. It supersedes BS EN ISO 14555:1998 which is withdrawn.
The UK participation in its preparation was entrusted to Technical Committee
WEE/-/1, Briefing committee for welding.
A list of organizations represented on WEE/-/1 can be obtained on request to its
secretary.
This publication does not purport to include all the necessary provisions of a
contract. Users are responsible for its correct application.
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Compliance with a British Standard cannot confer immunity from
legal obligations.
This British Standard was
published under the authority
of the Standards Policy and
Strategy Committee
on 30 November 2006
© BSI 2006
ISBN 0 580 49752 6
Amendments issued since publication
Amd. No.
Date
Comments
EUROPEAN STANDARD
EN ISO 14555
NORME EUROPÉENNE
EUROPÄISCHE NORM
October 2006
ICS 25.160.10
Supersedes EN ISO 14555:1998
English Version
Schweißen - Lichtbogenbolzenschweißen von metallischen
Werkstoffen (ISO 14555:2006)
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Soudage - Soudage à l'arc des goujons sur les matériaux
métalliques (ISO 14555:2006)
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Welding - Arc stud welding of metallic materials (ISO
14555:2006)
This European Standard was approved by CEN on 22 September 2006.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European
Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national
standards may be obtained on application to the Central Secretariat or to any CEN member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the official
versions.
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CEN members are the national standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France,
Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania,
Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36
© 2006 CEN
All rights of exploitation in any form and by any means reserved
worldwide for CEN national Members.
B-1050 Brussels
Ref. No. EN ISO 14555:2006: E
EN ISO 14555:2006
Foreword
This document (EN ISO 14555:2006) has been prepared by Technical Committee ISO/TC 44
"Welding and allied processes" in collaboration with Technical Committee CEN/TC 121
"Welding", the secretariat of which is held by DIN.
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This European Standard shall be given the status of a national standard, either by publication of
an identical text or by endorsement, at the latest by April 2007, and conflicting national
standards shall be withdrawn at the latest by April 2007.
This document supersedes EN ISO 14555:1998.
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According to the CEN/CENELEC Internal Regulations, the national standards organizations of
the following countries are bound to implement this European Standard: Austria, Belgium,
Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary,
Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland,
Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
Endorsement notice
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The text of ISO 14555:2006 has been approved by CEN as EN ISO 14555:2006 without any
modifications.
EN ISO 14555:2006
INTERNATIONAL
STANDARD
ISO
14555
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Second edition
2006-10-01
Welding — Arc stud welding of metallic
materials
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Soudage — Soudage à l'arc des goujons sur les matériaux métalliques
Reference number
ISO 14555:2006(E)
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EN ISO 14555:2006
Contents
Page
Foreword............................................................................................................................................................. v
Scope ..................................................................................................................................................... 1
2
Normative references ........................................................................................................................... 1
3
Terms and definitions........................................................................................................................... 2
4
4.1
4.2
Symbols and abbreviated terms ......................................................................................................... 4
Symbols ................................................................................................................................................. 4
Abbreviated terms ................................................................................................................................ 4
5
Technical review ................................................................................................................................... 5
6
6.1
6.2
Welding personnel................................................................................................................................ 5
Stud-welding operators........................................................................................................................ 5
Welding coordination ........................................................................................................................... 5
7
7.1
7.2
7.3
Equipment ............................................................................................................................................. 6
Production equipment.......................................................................................................................... 6
Description of the equipment .............................................................................................................. 6
Maintenance .......................................................................................................................................... 6
8
Production planning ............................................................................................................................. 7
9
9.1
9.2
9.3
9.4
9.5
9.6
9.7
9.8
9.9
9.10
9.11
9.12
9.13
Welding procedure specification (WPS)............................................................................................. 7
General................................................................................................................................................... 7
Information related to the manufacturer ............................................................................................ 7
Information related to the parent material ......................................................................................... 7
Welding process ................................................................................................................................... 7
Joint........................................................................................................................................................ 8
Studs ...................................................................................................................................................... 8
Auxiliaries.............................................................................................................................................. 8
Power source ........................................................................................................................................ 9
Movable fixtures.................................................................................................................................... 9
Welding variables ................................................................................................................................. 9
Thermal conditions............................................................................................................................. 10
Post-weld heat-treatment ................................................................................................................... 10
Non-thermal treatment after welding ................................................................................................ 10
10
10.1
10.2
10.3
10.4
10.5
Welding procedure qualification ....................................................................................................... 10
Principles ............................................................................................................................................. 10
Welding procedure tests .................................................................................................................... 10
Pre-production tests........................................................................................................................... 14
Previous experience ........................................................................................................................... 14
Welding procedure qualification record (WPQR) ............................................................................ 15
11
11.1
11.2
11.3
11.4
11.5
11.6
11.7
Examination and testing .................................................................................................................... 15
General................................................................................................................................................. 15
Visual examination ............................................................................................................................. 15
Bend testing ........................................................................................................................................ 15
Tensile testing..................................................................................................................................... 18
Torque test .......................................................................................................................................... 21
Macro examination ............................................................................................................................. 22
Radiographic examination ................................................................................................................. 22
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1
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Introduction ....................................................................................................................................................... vi
iii
EN ISO 14555:2006
Acceptance criteria ............................................................................................................................. 22
General ................................................................................................................................................. 22
Acceptance criteria for visual examination...................................................................................... 23
Acceptance criteria for bend testing................................................................................................. 23
Acceptance criteria for tensile testing.............................................................................................. 23
Acceptance criteria for torque testing .............................................................................................. 23
Acceptance criteria for macro examination ..................................................................................... 23
Acceptance criteria for radiographic examination .......................................................................... 23
Acceptance criteria for additional tests............................................................................................ 24
13
Workmanship....................................................................................................................................... 24
14
14.1
14.2
14.3
14.4
14.5
14.6
14.7
14.8
Process control ................................................................................................................................... 24
General ................................................................................................................................................. 24
Production test .................................................................................................................................... 25
Simplified production test.................................................................................................................. 25
Re-testing for production test or simplified production test.......................................................... 26
Production surveillance ..................................................................................................................... 26
Production surveillance record ......................................................................................................... 26
Non-conformance and corrective actions ........................................................................................ 26
Calibration of the measuring and testing equipment...................................................................... 27
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12
12.1
12.2
12.3
12.4
12.5
12.6
12.7
12.8
Annex A (informative) Processing of stud welding....................................................................................... 28
Annex B (normative) Quality requirements for stud welding ...................................................................... 48
Annex C (informative) Manufacturer's welding procedure specification (WPS)........................................ 49
Annex D (informative) Welding procedure qualification record form (WPQR) (for drawn-arc
stud welding with ceramic ferrule or shielding gas and short-cycle drawn-arc stud
welding)................................................................................................................................................ 50
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Annex E (informative) Welding procedure qualification record form (WPQR) (for capacitor
discharge stud welding with tip ignition and capacitor discharge drawn-arc stud welding) ..... 54
Annex F (informative) Test results — Production test (for drawn-arc stud welding with ceramic
ferrule or shielding gas and short-cycle drawn-arc stud welding) ................................................ 57
Annex G (informative) Test results — Production test (for capacitor discharge stud welding with
tip ignition and capacitor discharge drawn-arc stud welding)....................................................... 59
Annex H (informative) Example for production surveillance record........................................................... 61
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Bibliography ..................................................................................................................................................... 62
iv
EN ISO 14555:2006
Foreword
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ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
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International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 14555 was prepared by Technical Committee ISO/TC 44, Welding and allied processes, Subcommittee
SC 10, Unification of requirements in the field of metal welding.
This second edition cancels and replaces the first edition (ISO 14555:1998), which has been technically
revised.
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Requests for official interpretations of any aspect of this International Standard should be directed to the
Secretariat of ISO/TC 44/SC 10 via your national standards body. A complete listing of these bodies can be
found at http://www.iso.org.
v
EN ISO 14555:2006
Introduction
The purpose of arc stud welding is to weld predominantly pin-shaped metal parts to metal workpieces. In this
International Standard it is referred to simply as stud welding. Amongst other things, stud welding is used in
bridge building (especially in composite structures), steel structures, shipbuilding, facade-wall fabrication, vehicle
manufacture, equipment design, steam-boiler construction, and the manufacture of household appliances.
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The quality of a stud weld depends not only on strict compliance with the welding procedure specification but
also on the correct function of the actuating mechanism (e.g. welding guns), and on the condition of the
components, of the accessories and of the power supply.
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This International Standard does not invalidate former specifications, providing the technical requirements are
equivalent and satisfied.
vi
EN ISO 14555:2006
Welding — Arc stud welding of metallic materials
1
Scope
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This International Standard covers arc stud welding of metallic materials subject to static and dynamic loading.
It specifies requirements that are particular to stud welding, in relation to welding knowledge, quality
requirements, welding procedure specification, welding procedure qualification, qualification testing of
operators and testing of production welds.
This International Standard is appropriate where it is necessary to demonstrate the capability of a
manufacturer to produce welded construction of a specified quality.
NOTE
General quality requirements for fusion welding of metallic materials are given in ISO 3834-1, ISO 3834-2,
ISO 3834-3, ISO 3834-4 and ISO 3834-5.
This International Standard has been prepared in a comprehensive manner, with a view to its being used as a
reference in contracts. The requirements contained within it can be adopted in full, or partially, if certain
requirements are not relevant to a particular construction (see Annex B).
2
Normative references
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The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO 857-1, Welding and allied processes — Vocabulary — Part 1: Metal welding processes
ISO 3834-1, Quality requirements for fusion welding of metallic materials — Part 1: Criteria for the selection of
the appropriate level of quality requirements
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ISO 3834-2, Quality requirements for fusion welding of metallic materials — Part 2: Comprehensive quality
requirements
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ISO 3834-3, Quality requirements for fusion welding of metallic materials — Part 3: Standard quality
requirements
ISO 3834-4, Quality requirements for fusion welding of metallic materials — Part 4: Elementary quality
requirements
ISO 4063, Welding and allied processes — Nomenclature of processes and reference numbers
ISO 6947, Welds — Working positions — Definitions of angles of slope and rotation
ISO 9606-1, Approval testing of welders — Fusion welding — Part 1: Steels
ISO 9606-2, Qualification test of welders — Fusion welding — Part 2: Aluminium and aluminium alloys
ISO 13918:—1), Welding — Studs and ceramic ferrules for arc stud welding
1)
To be published. (Revision of ISO 13918:1998)
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EN ISO 14555:2006
ISO 14175, Welding consumables — Shielding gases for arc welding and cutting
ISO 14731, Welding coordination — Tasks and responsibilities
ISO 14732:1998, Welding personnel — Approval testing of welding operators for fusion welding and of
resistance weld setters for fully mechanized and automatic welding of metallic materials
ISO 15607:2003, Specification and qualification of welding procedures for metallic materials — General rules
ISO/TR 15608, Welding — Guidelines for a metallic materials grouping system
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ISO 15611, Specification and qualification of welding procedures for metallic materials — Qualification based on
previous welding experience
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ISO 15613, Specification and qualification of welding procedures for metallic materials — Qualification based on
pre-production welding test
ISO 15614-1:2004, Specification and qualification of welding procedures for metallic materials — Welding
procedure test — Part 1: Arc and gas welding of steels and arc welding of nickel and nickel alloys
ISO 15614-2, Specification and qualification of welding procedures for metallic materials — Welding procedure
test — Part 2: Arc welding of aluminium and its alloys
ISO 17636, Non-destructive testing of welds — Radiographic testing of fusion-welded joints
ISO 17662, Welding — Calibration, verification and validation of equipment used for welding, including
ancillary activities
Terms and definitions
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3
For the purposes of this document, the terms and definitions given in ISO 857-1, ISO 3834-1, ISO 4063,
ISO 14731, ISO 14732 and ISO 15607 and the following apply.
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3.1
stud
fastener to be attached by stud welding
3.2
auxiliaries
ceramic ferrules and shielding gases
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3.3
stud-welding operator
operating personnel for stud-welding equipment
NOTE
In special cases (e.g. mass production at the manufacturer's factory) the welding can be carried out by
suitable auxiliary personnel, appropriately trained and supervised.
3.4
stud diameter
d
stud nominal diameter
NOTE
See ISO 13918.
3.5
welding diameter
dw
diameter at the weld base
2
EN ISO 14555:2006
3.6
weld zone
welded area underneath the welding diameter
3.7
current intensity
root-mean-square (RMS) value of the welding current in the steady state during the burning time of the arc
NOTE
Current intensity is not applicable to capacitor discharge.
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3.8
welding time
time difference between the ignition and the final extinction of the main arc
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3.9
lift
L
distance between the stud tip and the work piece surface with the stud-lifting mechanism in position and
activated
NOTE 1
For tip ignition, this definition applies to the ignition gap.
NOTE 2
See Figure A.1.
3.10
plunge
axial movement of the stud towards the surface of the work piece
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3.11
protrusion
P
⟨unregulated lifting mechanism⟩ distance between the tip of the stud and the face of the support device in their
initial positions, where the support device faces the work piece
A spring-loaded lifting mechanism is an unregulated lifting mechanism.
NOTE 2
See Figure A.1.
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NOTE 1
3.12
arc blow
magnetic deflection of the arc from the axial direction of the stud
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3.13
flux
aluminium additive on the weld end of the stud, which improves the ignition and de-oxidizes the weld pool
3.14
dual-material stud
two-material stud composed of a material at the weld tip, similar to that of the parent material, and a dissimilar
material outside the weld tip, which are joined by a friction weld, thus avoiding a mixed structure in the weld
zone when stud welding
3.15
structure subjected to fatigue loading
structure subject to a set of typical load events described by the positions or movements of loads, their
variation in intensity and their frequency and sequence of occurrence
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EN ISO 14555:2006
4
Symbols and abbreviated terms
4.1
Symbols
d
stud diameter (expressed in mm)
dw
welding diameter (expressed in mm)
h
length of the threaded part of the nut
I
current intensity (expressed in A)
L
lift
P
protrusion
t
thickness of plate
tw
welding time (expressed in ms or s)
T
torque (expressed in Nm)
U
charging voltage (expressed in V)
W
charging energy (expressed in Ws)
a
bending angle (expressed in °)
4.2
Abbreviated terms
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capacitance (expressed in mF)
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C
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For the purposes of this International Standard, the following symbols apply.
For the purposes of this International Standard, the following abbreviated terms apply.
ceramic ferrule
HAZ
heat-affected zone
NP
no protection
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CF
PA
flat welding position
PC
horizontal welding position
PE
overhead welding position
pWPS
preliminary welding procedure specification
SG
shielding gas
WPS
welding procedure specification
WPQR
welding procedure qualification record
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EN ISO 14555:2006
5
Technical review
When a technical review is required by an application standard, by specification or by use of ISO 3834-2,
ISO 3834-3 or ISO 3834-4, the manufacturer shall check, as appropriate, the following aspects:
a) the accessibility and welding position of the stud weld;
b) the nature of the surface and the collar shape of the welded joint;
c) materials and combinations of materials (see Tables A.3 and A.4);
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d) the ratio of stud diameter to sheet metal thickness (avoidance of damage on the reverse side of the
sheet);
f)
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e) dimensions and details of the weld preparation and of the finished weld, including the nature of the stud
and sheet-metal surfaces, positional and angular accuracy and the length tolerance of the welded stud;
the use of special techniques to avoid damage to the reverse side of the sheet;
g) techniques to assure the angular position of the welded stud.
NOTE
Consideration is paid to the multi-axial stress state arising from localized heating/cooling. This stress
concentration reduces the dynamic strength of a component with welded studs.
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Stud-welding operators
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6.1
Welding personnel
Stud-welding operators shall be qualified in accordance with ISO 14732:1998, 4.2.1 or 4.2.2. They shall have
appropriate knowledge to operate the equipment, to adjust it properly, to carry out the welding correctly and,
while doing so, to pay attention to good contact and suitable connection between the work piece cables and
uniform distribution of ferromagnetic materials (see Table A.8).
The qualification shall include testing in accordance with the acceptance criteria specified in 12.2.
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A test of job knowledge is required for all qualification methods. This test shall cover, as a minimum:
setting up the welding equipment in accordance with the welding procedure specification;
b)
basic knowledge of the way in which suitable connection of work piece cables, the polarity of the stud,
and arc blowing can influence the weld result (see Table A.8);
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a)
c)
basic assessment of the welded joint for imperfections (see Tables A.5, A.6 and A.7);
d)
safe execution of the welding operations, i.e. good contact of the stud in the stud holder, no movement
during the welding process, operation checking and correct positioning of the guns).
6.2
Welding coordination
Welding coordination shall be performed in accordance with ISO 14731.
Welding coordination personnel for stud welding shall have knowledge of and experience in the relevant
stud-welding process, and shall be able to select and set the correct parameters, e.g. lift, protrusion (plunge),
current intensity, and welding time.
A welding coordinator is not required for stud welding to structures subjected to unspecified static loading (see
Annex B).
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EN ISO 14555:2006
7
Equipment
7.1
Production equipment
Suitable stud-welding equipment shall be used, with power supplies of sufficient capacity to weld the stud
properly to the parent material when the equipment is correctly set up. The following equipment shall be
available, as required:
power sources, control unit and movable fixtures;
b)
cables with sufficient cross-section, solid connection terminals and sufficient earth connection;
c)
handling equipment for the technical aspects of welding fabrication (jigs, fixtures);
d)
weld data monitoring equipment;
e)
post-drying equipment for ceramic ferrules;
f)
cleaning facilities for contact points and welding points;
g)
measuring and testing equipment;
h)
equipment for pre- and post-treatment;
i)
equipment and welding plant for retouching.
7.2
Description of the equipment
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a)
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A list of the stud-welding equipment shall be maintained, which shall serve as evidence of the performance
and stud-welding application field. It shall include:
details of the smallest and largest weldable stud diameter;
b)
the maximum number of studs to be welded per unit of time;
c)
the regulating range of the power supply;
d)
the mode of operation and performance of mechanized or automatic stud-welding equipment;
e)
details of the available test equipment.
7.3
Maintenance
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a)
The correct functioning of the equipment shall be ensured. During production, a function check of the
actuation mechanisms shall be performed at fixed intervals. Cables, terminals, stud and ceramic ferrule
holders shall be regularly checked and replaced at the appropriate time. For mass production and
comprehensive quality requirements in accordance with ISO 3834-2, a maintenance plan for additional
essential systems shall be drawn up. Examples of such systems are:
a)
stud sorting and feeding systems;
b)
stud and ceramic ferrule holders;
c)
mechanical guides and fixtures;
d)
measuring equipment;
e)
cables, hoses, connecting elements;
f)
a monitoring system.
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EN ISO 14555:2006
8
Production planning
For stud welding, the production planning shall also contain the following elements:
a definition of the required stud-welding procedures and equipment;
b)
details of which jigs and fixtures are used;
c)
the surface preparation method.
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Welding procedure specification (WPS)
9.1
General
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a)
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The welding procedure specification (WPS) shall give details of how a welding operation shall be performed
and shall contain all relevant information about the welding work.
Information listed in 9.2 to 9.13 is adequate for most welding operations. For some applications, it may be
necessary to supplement or reduce the list. The relevant information shall be specified in the WPS.
Ranges and tolerances shall be specified when appropriate. An example of the WPS format is given in
Annex C.
9.2
Information related to the manufacturer
9.2.1
Identification of the manufacturer
unambiguous identification.
9.2.2
⎯
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⎯
Identification of the WPS
alphanumeric designation (reference code).
9.2.3
Reference to the welding procedure qualification record (WPQR) or other relevant documents
alphanumeric designation (reference code).
9.3
Information related to the parent material
9.3.1
Parent material type
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⎯
⎯
identification of material, preferably by reference to an appropriate standard;
⎯
parent material(s) delivery condition.
NOTE
A WPS can cover a material group in accordance with ISO/TR 15608. See also ISO/TR 20172, ISO/TR 20173
and ISO/TR 20174.
9.3.2
Dimensions
⎯
the thickness or range of thickness of the parent material;
⎯
other relevant dimensions.
9.4
Welding process
⎯
designation in accordance with ISO 4063.
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EN ISO 14555:2006
9.5
Joint
9.5.1
Joint design
⎯
sketch of the joint design showing the relative positions of studs and tolerances;
⎯
the sequence of the welding of studs shall be indicated on the sketch if essential for application.
9.5.2
welding positions shall be specified in accordance with ISO 6947.
9.5.3
Preparation of parent material surface
method of surface preparation, if necessary (e.g. cleaning, degreasing, pickling);
⎯
maximum time permitted between preparation and welding (if required).
9.5.4
Jigs and fixtures
⎯
the methods to be used (if required);
⎯
fixture details, templates, etc.
9.5.5
Support
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⎯
the method of support;
⎯
specification of supporting material;
⎯
dimensions of support (when welding thin plates).
9.6
Studs
9.6.1
Designation
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⎯
⎯
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⎯
Welding position
Designation according to standard, supplier or trade name; non-standard studs shall be specified.
Handling
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9.6.2
⎯
if the studs are to be treated (e.g. by cleaning) before use, this shall be specified.
9.7
Auxiliaries
9.7.1
Ceramic ferrules (if any)
⎯
designation according to standard, supplier or trade name; non-standard ceramic ferrules shall be
specified;
⎯
if the ceramic ferrules are to be treated (e.g. by rebaking) before use, this shall be specified.
9.7.2
⎯
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Protective gas (if any)
designation in accordance with ISO 14175.
9.8
Power source
⎯
manufacturer, type.
9.9
Movable fixtures
9.9.1
Welding gun/head
⎯
manufacturer, type;
⎯
damper.
9.9.2
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EN ISO 14555:2006
Shielding gas system (if used)
gas flow rate;
⎯
(schematic) description showing nozzle dimensions and position of nozzle(s) in relation to stud and work
piece.
9.9.3
⎯
Stud feeding system (if any)
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⎯
description of stud feeding system including sketch.
9.10 Welding variables
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9.10.1 Drawn arc stud welding with ceramic ferrule or shielding gas and short-cycle drawn arc stud
welding
polarity;
b)
welding current;
c)
welding time;
d)
lift;
e)
protrusion;
f)
damper;
g)
number and position of earth clamps.
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9.10.2 Capacitor discharge drawn arc stud welding or capacitor discharge stud welding with tip
ignition
a)
polarity;
b)
capacitance;
c)
charging voltage;
d)
spring force and/or gap length;
e)
number and position of earth clamps;
f)
welding cable configuration (if used for current control).
9
EN ISO 14555:2006
9.11 Thermal conditions
a)
preheat temperature (if required);
b)
if preheating is not required, the lowest permitted ambient temperature.
9.12 Post-weld heat-treatment
9.13 Non-thermal treatment after welding
grinding, machining or any other mechanical treatment;
b)
pickling or any other chemical treatment;
c)
any special procedure for removal of ferrules.
10 Welding procedure qualification
10.1 Principles
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a)
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If, in special cases, any post-weld heat-treatment or ageing is necessary, specification of the procedure or
reference to a separate post-weld heat-treatment or ageing specification is required. This should include
specification of the entire thermal cycle.
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Preliminary welding procedure specifications (pWPS) for arc stud welding shall be prepared in accordance
with Clause 9 and qualified prior to production, whenever required. They shall specify the range for all the
relevant parameters. In principle, the following methods of qualification are permitted, but specification or
application code requirements can restrict the choice of method:
qualification by welding procedure test in accordance with 10.2;
b)
qualification by pre-production tests in accordance with 10.3;
c)
qualification based on previous experience in accordance with 10.4.
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a)
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All new welding procedure qualifications are to be in accordance with this International Standard from the date
of its issue. However, this International Standard does not invalidate previous welding procedure qualifications
made to former national standards or specifications, providing the technical requirements are satisfied and the
previous procedure qualifications are relevant to the application and production work on which they are to be
employed. Previous procedure qualifications to former national standards or specifications should be
considered at the time of the enquiry or contract stage and agreed between the contracting parties.
10.2 Welding procedure tests
10.2.1 Application
When welding procedure tests are required, these shall be carried out in accordance with the provisions in
10.2 of this International Standard, unless more severe tests are specified.
10.2.2 Proof of conformity of parent materials and stud materials
For the parent material and the stud material to be used, proof of conformity shall be available.
In the absence of such proof, the parent material and/or stud material shall be subjected to additional material
tests before the welding procedure tests. For this purpose, sufficient amounts of parent material and stud
material from the same melt as used in the test shall be made available.
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EN ISO 14555:2006
10.2.3 Shape and dimensions of test pieces
The dimension of the test piece(s) shall be sufficient to carry out all tests. The thickness of the test pieces
shall be chosen so that the plate or flange thickness proposed for production is covered (see 10.2.8.6).
10.2.4 Welding
Preparation, set-up and welding of test pieces shall be carried out in accordance with the pWPS, under the
general conditions of production welding that they represent. The same welding positions shall be observed
as on the actual work piece. There shall be sufficient distance from the lateral earth clamps.
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Welding procedure tests shall be carried out on the smallest and largest stud diameters used in practice.
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As a minimum, the numbers of studs indicated in Table 1 shall be welded in the welding procedure test.
Table 1 — Numbers of studs to be welded in the welding procedure test
Welding process
Number of studs to be
welded
Drawn arc stud welding with ceramic ferrule or shielding gas (d u 12 mm)
12
For black-white combinations
22
Drawn arc stud welding with ceramic ferrule or shielding gas (d > 12 mm)
17
Short-cycle drawn arc stud welding
12
20
Capacitor discharge drawn arc stud welding
30
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When using torque tests instead of macro examination
Capacitor discharge stud welding with tip ignition
30
NOTE
For setting-up tests and replacement specimens (see Clause 14), it is recommended that a sufficient number of additional
studs be provided on the test pieces.
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Welding and testing of the test pieces shall be witnessed by an examining body (see ISO 15607:2003, 3.9).
10.2.5 Scope of examination and testing
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The examination and testing includes non-destructive and destructive tests, which shall be in accordance with
the requirements of Tables 2, 3 and 4.
All inspection and tests shall be performed in accordance with the procedures specified in Clause 11. The
number and type of test stated in Tables 2, 3 and 4 shall only be used in the case of the qualification of a
pWPS based on the use of stud material and parent material, as specified in Table A.3.
10.2.6 Acceptance criteria
The acceptance criteria described in Clause 12 shall be fulfilled unless otherwise specified.
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EN ISO 14555:2006
Table 2 — Examination and testing of test pieces welded by drawn arc stud welding with ceramic
ferrule or shielding gas
Number of studs to be tested
Type of test
Application > 100 °C
Application u 100°C
dw > 12 mm
dw u 12 mm
Visual examination
All diameters (d)
all
Bend testing 60° (see Figures 1a), 1b) or 1c))
10
not applied
Bend testing by means of torque wrench (see
Figure 2)
not applied
10
not applied
Macro examination (off-set 90° through the centre
of the stud)
a
5b
—
5 b (optional instead
—
of tensile testing)
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Radiographic examination
10 a
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Tensile testing (see Figures 3, 4 or 5)
2
Tensile testing is only required for welds between stud material of group 8, in accordance with ISO/TR 15608, and parent material
of material group 1 or 2, in accordance with ISO/TR 15608.
b
Only for structures subjected to fatigue loading.
Table 3 — Examination and testing of test pieces welded by short-cycle drawn arc stud welding
with dw u 12 mm
Visual examination
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Type of test
Bend testing 60° (see Figures 1a), 1b) or 1c))
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Torque test (see Figure 6) or macro examination (off-set 90° through the centre of
the stud)
Number of studs to be tested
All
10
10 (torque test)
2 (macro examination)
Table 4 — Examination and testing of test pieces welded by capacitor discharge stud welding
with tip ignition and capacitor discharge drawn arc stud welding
Type of test
Number of studs to be tested
All
Tensile testing (see Figures 3, 4 or 5)
10
Bend testing 30° [see Figures 1a), 1b) or 1c)]
20
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Visual examination
10.2.7 Re-testing
If one of the studs fails to meet the requirements, two similar replacements studs can be taken from the
associated test pieces. If this is not possible, equivalent studs shall be welded subsequently. It is therefore
recommended that a sufficient number of replacement studs be provided for the welding procedure tests.
If more than one stud, or one of the two replacement studs, does not satisfy the requirements, the test has
failed.
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EN ISO 14555:2006
10.2.8 Range of qualification
10.2.8.1
General
All the conditions of validity stated below shall be met independently of each other.
Changes outside of the ranges specified shall require a new welding procedure test.
There is no limit to the duration of the validity of the welding procedure qualification, provided that no quality
changes are made and that a production surveillance record is kept in accordance with 14.6.
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However, since the result of stud welding depends not only on compliance with the welding procedure
specification, but also, for example, on the way that the mechanical capability of the welding guns is critical in
terms of weld quality, a production test shall be carried out at least once a year, as specified in 14.2.
10.2.8.2
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In the event of production being suspended for more than one year, the validity of the welding procedure
qualification shall be confirmed in a production test.
Conditions related to the manufacturer
The qualification of a pWPS obtained by a manufacturer is valid for welding in workshops or sites under the
same technical and quality control of that manufacturer.
10.2.8.3
Conditions related to the welding process
The qualification is valid only for the welding process used in welding procedure test.
Conditions related to the parent material
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10.2.8.4
A welding procedure test carried out with one of the steels of a material group, in accordance with
ISO/TR 15608, covers the steels with lower specified yield strength of this material group, or the lower alloyed
steels of the same material group for the intentional added elements, but not for fortuitous impurities. In
accordance with ISO/TR 15608, material group 3 covers material group 1 and material group 2, whilst material
group 21 covers material group 22, and vice versa.
Stud material
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10.2.8.5
Welding procedure tests cover all materials of the same material group in accordance with ISO/TR 15608 with
the following addition:
For drawn-arc stud-welding processes up to 13 mm diameter, material groups 8 and 10 cover material
groups 1 and 2.1 and vice versa.
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a)
b)
For capacitor discharge stud-welding processes, material group 8 covers material groups 1 to 6 and 11.1
and vice versa.
c)
Material group 21 covers material group 22 and vice versa.
10.2.8.6
Parent material thickness
As recommended in Table A.1, the material thickness used for the welding procedure test applies to all
thicknesses which exceed those specified in Table A.1, providing the pWPS used in the welding procedure
test applies.
For material thicknesses below the recommended minimum thickness, a new welding procedure test is
required.
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EN ISO 14555:2006
10.2.8.7
Conditions related to the stud diameter and shape
A single welding procedure test covers all stud shapes, but only the diameters used in the test.
Two welding procedure tests on different diameter studs cover the range between the two diameters and all
stud shapes.
10.2.8.8
Conditions related to the welding position
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Using drawn arc stud welding with ceramic ferrule or shielding gas and short-cycle drawn arc stud welding,
welding position PC covers welding positions PE and PA, but not vice versa. For welding position PC, special
ceramic ferrules can be used. Welding position PE covers welding position PA, but not vice versa.
10.2.8.9
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Using capacitor discharge stud welding with tip ignition and capacitor discharge drawn arc stud welding, a
welding procedure test carried out in any one welding position is valid for welding in all welding positions.
Conditions related to the welding equipment
If there is a change in the type of welding gun or head, and/or power source, or welding equipment
manufacturer, the welding procedure specification shall be verified by a production test.
10.2.8.10 Preheating
Welding procedure specifications that have been qualified by a welding procedure test without preheating are
also valid for those for welding with preheating, but not vice versa.
10.3 Pre-production tests
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The general provisions of ISO 15613 shall be adhered to, with the following additions and modifications:
welding procedure specifications, pWPS and WPS, shall conform to the provisions of Clause 9;
b)
the actual production shall be controlled by a suitable scheme for process control;
c)
the number of studs (produced items) tested shall meet the requirements of 10.2.4, if possible;
d)
qualification is limited to the same type of equipment, the same type and thickness of the parent material
and the same diameter of studs as used during the pre-production test.
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a)
10.4 Previous experience
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The general provisions of ISO 15611 shall be adhered to, with the following additions and modifications:
a)
welding procedure specifications, pWPS and WPS, shall conform to the provisions of Clause 9;
b)
the former production on which the experience is based shall have been controlled by a suitable scheme
for process control, giving a statistical confidence compatible with the future application of the welding
procedure to be qualified;
c)
qualification is limited to the same type of equipment, the same type and thickness of the parent material
and the same diameter of studs as used during the production on which the experience is based.
The use of previous experience instead of welding procedure tests is not permitted for steel welds with
standard or comprehensive quality requirements (see Annex A).
14
EN ISO 14555:2006
10.5 Welding procedure qualification record (WPQR)
The welding procedure qualification record (WPQR) is a statement of the results of assessing each test piece,
including re-tests. The relevant items listed for the WPS in Clause 9 shall be included, together with details of
any features that would be rejected on the basis of the requirements in Clause 11. If no rejectable features or
unacceptable test results are found, a WPQR detailing the welding procedure test piece results is qualified,
and shall be signed and dated by the examiner or test body.
A WPQR format, as shown in Annex D or Annex E, may be used to record details for the welding procedure
and the test results, in order to facilitate uniform presentation and assessment of the data.
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11.1 General
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11 Examination and testing
The methods described in 11.2 to 11.7 may be used for examination and testing of stud welds. Tests shall be
selected according to the application.
In certain stud-welding applications, e.g. steam boilers, shipbuilding or nuclear industry, additional tests (e.g.
hardness tests or ultrasonic examinations) may be required by application standards or specifications.
11.2 Visual examination
For drawn arc stud welding with ceramic ferrule or shielding gas and short-cycle drawn arc stud welding,
visual examination is used for assessing the following, as appropriate for the application:
the uniformity of the shape and the size of the collar (guidance values for drawn arc stud welding with
ceramic ferrule are given in ISO 13918), and
b)
location, length and angle of the stud after welding.
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a)
For capacitor discharge drawn arc stud welding and capacitor discharge stud welding with tip ignition, visual
examination is used for assessing the uniformity of the spatter ring.
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11.3 Bend testing
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The test serves as a simple bench test for approximate checking of the chosen welding data. In the test, the
weld is subjected to bending in an undefined manner. If arc blow or another visible imperfection is suspected,
the stud shall be bent in a manner such that the area to be examined is in the tension zone. This can be done
by one of the two following methods.
a)
The studs are bent through 60° using drawn arc stud welding with ceramic ferrule or shielding gas, or
short-cycle drawn arc stud welding, through 30° using capacitor discharge stud welding with tip ignition or
capacitor discharge drawn arc stud welding (see Figure 1).
b)
The studs are stressed by applying a bending moment below the elastic limit (see Figure 1).
NOTE
Values of bending moments for studs by applications > 100 °C are given in Table 5.
15
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EN ISO 14555:2006
b)
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a)
c)
Key
1
2
stud
work piece
3
tool
α
bending angle
Figure 1 — Examples for bend testing
16
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EN ISO 14555:2006
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a) Torque wrench for bend testing
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Figure 2 — Examples for bend testing by means of torque wrench
17
EN ISO 14555:2006
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Dimensions in millimetres
b) Test tool for bend testing
Key
d1 stud diameter +0,3 mm
d2 tool diameter
drive dimension
stud
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S
1
NOTE 1
The tool diameter can be chosen freely by the manufacturer, depending on the stud spacing.
NOTE 2
The drive dimension depends on the tool
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Figure 2 (continued)
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Table 5 — Bending moments based on stud diameter
Stud diameter
d
Bending moment
mm
Nm
8
40
10
60
12
85
The acceptance criteria given in 12.3 shall be fulfilled unless otherwise specified.
11.4 Tensile testing
By using a suitable tension device (see Figures 3, 4 or 5) the welded studs are pulled axially until fracture. The
test only applies to studs by application u 100 °C.
18
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EN ISO 14555:2006
Key
1
stud
2
3
steel nut
washer
4
5
sleeve
collar
6
work piece
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Figure 3 — Example for tensile testing of threaded studs
19
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EN ISO 14555:2006
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a)
b)
Key
1
stud (shear connector)
2
3
collar
bridge
4
5
work piece
screw for levelling
6
7
hydraulic cylinder
washer
NOTE
The washer is required for hardness 40 to 55 HRC.
Figure 4 — Examples for tensile testing of shear connectors
20
EN ISO 14555:2006
Key
1
stud
2
3
work piece
tensile device
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Figure 5 — Example for tensile testing of non-threaded studs
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11.5 Torque test
Key
d
stud diameter
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Weld resistance is checked by applying a torque T on a cap nut fully tightened on the stud (see Figure 6).
length of the threaded part of the nut
thickness of plate
T
torque
Minimum values of the required torque on mild steel are given in Table 6.
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NOTE
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t
Figure 6 — Example of torque test
21
EN ISO 14555:2006
Minimum thickness of the plate
t
mm
Stud diameter
d
Torque
T
Nm
M3
1,2
M4
3
M5
6
M6
9
M8
24
M10
46
M12
80
1,5
11.6 Macro examination
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0,7
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Table 6 — Minimum values of required torque on mild steel
The macro examination serves to check the shape and depth of the penetration. The assessment shall be
carried out with a maximum of tenfold magnification.
Macro examination is only required for the welding processes, drawn arc stud welding with ceramic ferrule or
shielding gas, and short-cycle drawn arc stud welding. For the specimen, a stud which has passed the bend
test may be chosen.
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11.7 Radiographic examination
The radiographic examination serves to check the weld area for internal imperfections. Radiographic
examination is only required for the welding process, drawn arc stud welding with ceramic ferrule or shielding
gas above d > 12 mm for applications u 100 °C, when tensile tests are not carried out.
The studs shall be cut off just over the collars.
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Radiography shall be carried out in accordance with ISO 17636, using class B technique.
The imperfections shall be in accordance with limits specified in 12.1.
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12 Acceptance criteria
12.1 General
The welds of the studs shall be free of imperfections, except those which are to be accepted by the different
tests and examinations.
The acceptance criteria shall be in accordance with 12.2 to 12.8, unless otherwise specified in application
standards or specifications.
If comprehensive quality requirements are required in accordance with ISO 3834-2, the total area of all
imperfections shall not exceed 5 % of the stud area. No individual imperfection on the fracture surface of the
weld shall be larger than 20 % of the stud diameter. Even for small imperfections, the number of imperfections
shall not exceed the value of the stud diameter in mm. Pores with a diameter of less than 0,5 mm are
disregarded.
22
EN ISO 14555:2006
If standard quality requirements are required in accordance with ISO 3834-3, the total area of all imperfections
shall not exceed 10 % of the stud area.
If elementary quality requirements are required in accordance with ISO 3834-4, the limit of the imperfections
shall be specified.
12.2 Acceptance criteria for visual examination
For drawn arc stud welding with ceramic ferrule or shielding gas, and short-cycle drawn arc stud welding, the
imperfections shown in Table A.5, Nos. 2 to 5, and the imperfections shown in Table A.6, Nos. 2 and 5, are
not acceptable.
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12.3 Acceptance criteria for bend testing
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For capacitor discharge drawn arc stud welding and capacitor discharge stud welding with tip ignition, the
imperfections shown in Table A.7, Nos. 2 to 4, are not acceptable.
A weld passes the test if no cracks are found in the weld after bending of the stud through 30° or 60°.
If a low-deformation fracture occurs in the heat-affected zone, the weldability of the materials shall be checked
(e.g. tendency to hardening).
If inhomogeneous deformation has to be expected due to the geometry of the stud, e.g. for studs with reduced
base, or if a bend until the mentioned angle is not possible, e.g. for studs of short length in relation to diameter,
for two-material studs and for studs with yield strength above 355 N/mm 2, the suitability of the weld shall be
shown by other means. A sufficient plastic deformability shall be achieved.
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Cracks which arise from the thread bottom are disregarded.
12.4 Acceptance criteria for tensile testing
A fracture in the weld area is not permitted, if comprehensive quality requirements in accordance with
ISO 3834-2 are required.
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If standard quality requirements in accordance with ISO 3834-3 are required, fractures within the weld zone
are only permitted if the nominal tensile strength of the stud material is reached. Imperfections in the fracture
surface shall be in accordance with the limits specified in 12.1.
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By use of flanged stud and the welding processes, capacitor discharge drawn arc stud welding or capacitor
discharge stud welding with tip ignition fractures within the weld zone are permitted, if the non-welded area
does not exceed 35 % of the flanged area.
12.5 Acceptance criteria for torque testing
The required torque shall be reached without weld failure.
12.6 Acceptance criteria for macro examination
Imperfections with dimensions larger than specified in 12.1 are not acceptable.
In the case of applications > 100 °C, a sufficient weld between stud and tube material has to be achieved
whilst leaving a minimum of 2 mm wall thickness non molten in the tube. In the case of undershooting this
value, the actual conditions shall be proven by calculation.
12.7 Acceptance criteria for radiographic examination
Imperfections with dimensions larger than specified in 12.1 are not acceptable.
23
EN ISO 14555:2006
12.8 Acceptance criteria for additional tests
Acceptance criteria for additional tests shall be specified. For the assessment, the characteristics of the
stud-welding process shall be taken into account.
EXAMPLE
permitted.
For the hardness test, higher hardness values than those specified in ISO 15614-1:2004, Table 2, are
13 Workmanship
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Surfaces to be welded shall be maintained dry and free from condensation. When material temperatures are
below 0 °C, appropriate preheating may be necessary. For reasons of weldability, the carbon content of the
steels should be u 0,22 %.
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Depending on the welding process, ceramic ferrules and/or shielding gases are used for protection or to
concentrate the arc. The ceramic ferrules shall be correctly chosen for the stud diameter and the type of stud.
The following points shall be observed:
a)
the ceramic ferrules shall be stored in a dry place;
b)
wet ceramic ferrules shall be rebaked at elevated temperatures before use (1 h above 900 °C);
c)
the ceramic ferrule shall be pressed against the parent material;
d)
the ceramic ferrule shall fit centrally with respect to the stud.
Tilting or uneven contact of the ceramic ferrule at the stud leads to an uneven collar and can inhibit plunging.
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NOTE
In special cases (drawn-arc stud welding of aluminium and its alloys or CrNi steels) it may be necessary to
use shielding gases. In principle, the ceramic ferrule can be replaced by shielding gas (for restrictions, see
Table A.1). The gas is fed to a device that shall ensure uniform gas shielding without turbulence. Note also the
following points:
the gas feed should be sealed off on the stud side;
⎯
the gas shall displace the atmosphere before welding starts, so a defined pre-flow time shall be observed;
⎯
in the case of aluminium, particularly careful gas shielding is essential.
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⎯
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14 Process control
14.1 General
For quality assurance, various quality requirements shall be met, depending on the stud-welding process and
the field of application (see Annex B). Before, during and after production, tests shall therefore be performed.
The various tests are as follows:
a)
production test;
b)
simplified production test;
c)
production surveillance.
These tests can be carried out by using the actual production pieces or by using special test pieces. The
pieces shall correspond to the production conditions.
24
EN ISO 14555:2006
14.2 Production test
14.2.1 General
Production tests shall be performed by the manufacturer before the beginning of welding operations on a
construction or a group of similar constructions, and/or after a specified number of welds. This number shall
be taken from the relevant application standard or shall be laid down in the specification.
The production test is limited to the stud diameter used, the parent material and the type of equipment.
14.2.2 Production test for drawn-arc stud welding with ceramic ferrule or shielding gas and
short-cycle drawn-arc stud welding
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At least ten studs shall be welded. For setting-up tests and, where appropriate, replacement tests, a sufficient
number of additional studs should be provided on the test piece. The following examinations and tests shall be
performed:
a)
visual examination (all studs);
b)
bend testing (five studs);
c)
macro examinations of two different studs (off-set by 90° through the centre of the stud).
NOTE
For short cycle drawn-arc stud welding, macro examinations can be replaced by torque tests (five studs).
The examinations and testing are performed and evaluated in accordance with Clause 11.
The results of the production test shall be documented (see Annex F).
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14.2.3 Production test for capacitor discharge stud welding with tip ignition and capacitor discharge
drawn-arc stud welding
At least ten studs shall be welded. For setting-up tests and, where appropriate, replacement tests, a sufficient
number of additional studs should be provided on the test piece. The following examinations and tests shall be
performed:
visual examination (all studs);
b)
tensile testing (three studs);
c)
bend testing (five studs).
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a)
The examination and tests are performed and evaluated in accordance with Clause 11.
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The results of the production test shall be documented (see Annex G).
14.3 Simplified production test
Simplified production tests shall be performed by the manufacturer before the start of each shift. They can
also be requested after a certain number of welds, by the application standard rules or in the specification.
The purpose of the simplified production test is to check that the equipment is correctly set up, and that it is
operating correctly. Three studs shall be welded. The simplified production tests comprise at least the
following test and examination:
a)
visual examination (all studs);
b)
bend testing (all studs).
The examination and test are performed and evaluated in accordance with Clause 11.
The results of the simplified production test shall be documented.
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EN ISO 14555:2006
14.4 Re-testing for production test or simplified production test
If one of the studs does not meet the requirements, two additional studs of the same type can be taken from
the associated test piece. If this is not possible, similar studs shall be additionally welded.
NOTE
This necessitates that a sufficient quantity of replacement specimens be provided in a production test.
If one of the additional studs does not satisfy the requirements, corrective action (see 14.7) shall be taken and
the production test shall be repeated.
14.5 Production surveillance
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14.5.1 Visual examination
14.5.2 Checking the welding parameters
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Visual examination is generally sufficient for production surveillance and shall cover all welds.
The relevant welding parameters shall be checked regularly.
NOTE
They can be monitored by suitable equipment.
14.5.3 Other non-destructive examinations and tests
If specified in the application standard, non-destructive testing may be added to production surveillance.
Suitable techniques are:
checking the length of the studs after welding;
b)
tensile test, bend test, torque test with restricted values.
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a)
14.6 Production surveillance record
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The manufacturer keeps a production surveillance record, which contains the results of the production test,
simplified production test and production surveillance. The manufacturer shall keep a different record for each
stud-welding process and the record shall be kept available, with the results of all tests recorded. Annex H is
an example form and should be used, where appropriate.
14.7 Non-conformance and corrective actions
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If there is an indication of non-conforming welding, e.g. porosity, collar not complete or unequal, or if the
length of one stud is outside the specification, a bend test (15°) or tensile test (limited to the design strength)
shall be performed on that stud. If the stud weld fails to satisfy the requirements in this test, three welds made
before and, where appropriate, after the defective weld shall also be subjected to bend or tensile testing.
If one of these studs also fails to satisfy the requirements in the test, appropriate testing shall be carried out on
all studs on the same work piece.
Corrective actions shall be taken for all non-conforming stud welds, either by removal of the defective stud,
where necessary, and repeat stud welding, or by repair welding with a suitable welding process. In isolated
cases, stud welding processes may be replaced by other suitable welding processes. Depending on the stud
diameter, a fillet weld shall reach the calculated throat.
NOTE
Sometimes defective studs do not need to be removed, but can be substituted by extra studs.
Alternative welding procedures shall be qualified in accordance with ISO 15614-1 or ISO 15614-2, and
welders shall be qualified in accordance with ISO 9606-1 or ISO 9606-2.
26
EN ISO 14555:2006
All repaired or replaced studs shall be tested in accordance with the specifications.
In addition, steps shall be taken to ensure that factors adversely affecting the stud welding are identified and
compensated.
14.8 Calibration of the measuring and testing equipment
In the case of comprehensive quality requirements in accordance with ISO 3834-2, the manufacturer shall be
responsible for the appropriate calibration of inspection, measuring and testing equipment. All equipment shall
be suitably controlled and shall be calibrated at specified intervals (see ISO 17662). See also Annex B.
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NOTE
In the case of drawn-arc stud-welding processes, this applies particularly to current intensity and welding time
measurement.
27
EN ISO 14555:2006
Annex A
(informative)
Processing of stud welding
A.1 General
This annex gives general guidance for the satisfactory production and control of stud welding.
A.2 Welding processes
A.2.1 Drawn arc stud welding
A.2.1.1
General
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In stud welding, an arc is briefly struck between the face of the stud and the work piece; both parts start to
melt and are then joined. Depending on the nature of the ignition method, a distinction is made between
drawn-arc stud welding and stud welding with tip ignition. Each method requires suitable power supplies,
actuating devices, studs and accessories (e.g. ceramic ferrules). A feature of stud welding is the very short arc
burn time (approximately 0,5 ms to 3 000 ms) and the associated high rate of heating and cooling. Normally
the diameter of the stud can range up to 10 mm for tip ignition welding, and up to 25 mm for drawn-arc
welding.
ww
w.
bz
f
Drawn arc stud welding can be done mechanically or automatically, using welding guns or welding heads. The
stud is inserted into the stud holder and - fitted with a ceramic ferrule, if necessary - applied to the work piece.
At the beginning of the welding process, the stud is lifted by the mechanism and, normally, first a pilot arc,
then the main arc, are struck between the tip of the stud and the work piece. This causes the face of the stud
and the parent material to melt. When the welding time has elapsed, the stud is plunged with little force
(< 100 N) into the molten pool, and the current source is switched off. The ceramic ferrule is then removed.
Figure A.1 shows the sequence of events using a ceramic ferrule.
28
m
EN ISO 14555:2006
P
xw
.c
o
Key
L lift
protrusion
X
time
Y
Z
current
stud movement
Figure A.1 — Stud movement in drawn-arc stud welding
A.2.1.2
Methods of drawn-arc stud-welding processes
bz
f
A distinction is made between three methods of welding processes (see Table A.1).
Drawn arc stud welding with ceramic ferrule or shielding gas (783).This welding process is generally
used in the 3 mm to 25 mm diameter range, with welding times of 100 ms to 3000 ms. It is usually carried
out with a ceramic ferrule or shielding gas, or with both, or in special cases without pool protection. This
method is used for the majority of applications. The minimum sheet thickness is 0,25 d for CF and 0,125 d
for SG, but not less than 1 mm.
b)
Short-cycle drawn-arc stud welding (784). A welding time of u 100 ms is used. This variant is suitable
for stud diameters up to 12 mm, but for the range between approximately 8 mm and 12 mm, stud
diameter shielding gas should be used to prevent increased pore formation. For aluminium, shielding gas
shall be used. The fusion zone is narrow and the thermal input modest, so that studs up to 12 mm
diameter can be welded to thin sheets. For diameters up to 9 mm diameter and with steel, the operation
is frequently carried out without protection of the weld pool and calls for studs with an upset flange, as
these afford a larger weld area than the plain stud-shaft diameter and thus reach a higher tensile force
than the stud shaft, despite pores in the weld zone. The minimum sheet thickness is 0,125 d, but not less
than 0,6 mm.
ww
w.
a)
c)
Capacitor discharge drawn-arc stud welding (785). Very short welding time (< 10 ms) can be achieved
by using a capacitor discharge power source. The diameter range is 3 mm to 10 mm. The minimum sheet
thickness is 0,1 d, but not less than 0,5 mm. The welding process is similar to the short-cycle drawn-arc
stud-welding process, but the peak current can be up to 4 000 A.
The working range of the various drawn-arc stud-welding processes is given in Table A.1.
29
EN ISO 14555:2006
Table A.1 — Working range of the various drawn-arc stud-welding processes
Weld pool
protection
3 to 25 PA
3 to 20 PE
3 to 16 PC
300 to 3 000
CF
0,25d, but not less
than 1 mm c
> 100
3 to 16 PA
3 to 8 PC
300 to 2 000
SG
0,125d, but not less
than 1 mm c
Short-cycle
drawn-arc stud
welding (784)
< 100
3 to 12, all welding
positions
Up to 1 800
NP, SG
0,125d, but not less
than 0,6 mm c
Capacitor discharge
drawn-arc stud
welding (785)
< 10
3 to 10, all welding
positions
Up to 4 000
(peak)
NP, (SG)
Drawn-arc stud
welding with ceramic
ferrule or shielding
gas (783)
> 100
a
In accordance with ISO 4063.
b
In accordance with ISO 6947.
Welding diameter,
dw, and welding
positions b
mm
c
Minimum sheet
thickness
mm
0,1d, but not less than
0,5 mm
xw
.c
o
Welding time
tw
ms
m
Current
intensity
I
A
Welding
processes a
The minimum sheet thickness avoids the risk of burning through the sheet. Other application requirements may call for greater
thicknesses.
When the high-power welding process (narrow melt zone), short-cycle welding process or the capacitor
discharge process is used, the stud tips shall be matched to the fusion penetration shape in the work piece
and made flatter (e.g. 166° cone angle).
Weld pool protection
bz
f
A.2.1.3
A distinction is made between different techniques on the basis of weld pool protection.
a)
Ceramic ferrule (CF). The ceramic ferrule has several functions:
⎯ protection of the weld pool by creation of metal vapour in the burning chamber at sufficient current
intensity;
concentration and stabilization of the arc, thus reducing arc blow;
⎯
moulding of the displaced weld pool to a weld collar and supporting of the weld pool.
w.
⎯
ww
Furthermore, it shields the operator from both arc and spatter. The ceramic ferrule is used for one weld
only and is removed once the molten metal has solidified.
b) Shielding gas (SG). In stud welding with shielding gas, the atmosphere is displaced from the arc region
by a shielding gas supplied from outside, which greatly reduces the formation of pores. For steels and
most other metals, a mixture of argon and carbon dioxide (ISO 14175 -M21) is widely used. For
aluminium and its alloys, pure argon Ar 99,99 (ISO 14175 -I1) or Argon-Helium mixtures (ISO 14175 -I3)
are widely used.
The shielding gas influences the arc and affects the fusion of the stud and work piece. It also influences
the shaping of the weld collar and the penetration shape, via the surface tension. A fundamental principle
is that the welding position PA, in accordance with ISO 6947, should be preferred for welding time > 100
ms. An additional ceramic ferrule can also be used to improve the shape of the collar and restrict the arc
to the immediate area of the work piece.
c) No protection (NP). Stud welding without protection is possible only for small welding diameters
(< 10 mm) and with short welding times (< 100 ms). Among the drawbacks of this method are severe
oxidation of the weld zone, increased pore formation and an irregular weld collar.
30
EN ISO 14555:2006
A.2.2 Capacitor discharge stud welding with tip ignition (786)
The two techniques for capacitor discharge stud welding with tip ignition are with contact or with gap.
Table A.2 — Characteristics for capacitor discharge stud welding with tip ignition
Characteristic
Contact
method
Gap
method
a
Welding
diameter
Peak
current
Welding
time
Spring
force
Plunging
speed
dw
≈
I
≈
≈
≈
mm
A
ms
N
m/s
786
0,8 to 10
786
0,8 to 10
(aluminium
up to 6)
Ignition
5 000
10 000
In accordance with ISO 4063.
1 to 3
0,5 to 2
Typical
application
m
Welding
process a
Welding of
(unalloyed and
alloyed) steel,
galvanized or
oily surfaces
60 to 100
depending
on piston
mass
0,5 to 0,7
40 to 60
Mostly
Welding of
0,5 to 1,
correct,
aluminium 1 advanced aluminium and
brass
up to 1,5
ignition
possible
xw
.c
o
Method
Always
correct
bz
f
In welding with contact, the stud is inserted into the stud holder of the machine [see Figure A.2 a)] and
positioned with its ignition tip directly on the surface of the component [see Figure A.2 b)]. A spring in the
welding gun presses the stud against the metal. Once the capacitor power has been switched on, the ignition
tip abruptly explodes and vaporizes partially, and the arc is generated [see Figure A.2 c)]. The stud is
advanced still further towards the sheet metal and finally remains in the solidified melt [see Figure A.2 d)]. The
welding time is u 3 ms.
w.
The difference between welding with gap and the technique described above is that, before welding begins,
the stud is held at a defined, adjustable distance from the work piece [see Figure A.2 a)].
When the capacitor bank is switched on, the stud is speeded up towards the surface of the metal, and the
welding process continues as described above [see Figures A.2 b), A.2 c) and A.2 d)]. A welding time of about
1 ms makes it possible, among other things, to weld aluminium and its alloys without gas shielding.
ww
The recommended sheet thickness should be W 0,1 d but not less than 0,5 mm.
a)
b)
c)
d)
Figure A.2 — Capacitor discharge stud welding with tip ignition — Main phases of the welding process
31
EN ISO 14555:2006
A.2.3 Parent materials
A.2.3.1
General
m
The brief arc effect initiates melting of both stud and parent material, and the molten metals intermix as the
joint is formed. This phenomenon differs in the various stud-welding processes. Generally speaking, more
stud material melts than parent material. The weld area on the parent material is usually larger than the
cross-section of the stud. The strength and deformation properties at the transition from weld to stud shall
therefore be investigated with special attention. The surface of the parent material should be clean. Layers of
paint, rust, scale, grease and coatings of non-weldable metals should be removed from the weld location. This
can be done mechanically or chemically. Parent materials with scale and rust layers shall be thoroughly
ground off. The surface preparation shall be specified in the WPS. Where welding times are short (< 50 ms),
the surface should be cleaned with particular care.
xw
.c
o
A.2.3.2 Parent material for drawn-arc stud welding with ceramic ferrule or shielding gas and
short-cycle drawn-arc stud welding
Parent materials for this type of stud welding are those listed in Table A.3.
The use of other steel grades and other materials such as lead-free brass for drawn-arc stud welding, can
also be permitted. In such cases, additional or other tests, as described in Clause 11, can be required.
A.2.3.3 Parent material for capacitor discharge drawn-arc stud welding and capacitor discharge stud
welding with tip ignition
Parent materials for this type of stud welding are those listed in Table A.4.
A.2.4 Studs
A.2.4.1
Stud material
bz
f
The use of other materials is also permitted. In such cases, alternative or additional tests, such as those
described in Clause 11, may be required.
A.2.4.2
w.
Stud materials are listed in ISO 13918:—, Table 2.
Stud shapes
ww
The stud shape outside the weld area can be chosen freely. The shape of the stud tip differs according to
welding process and material (see ISO 13918).
32
EN ISO 14555:2006
A.2.5 Combinations of stud material and parent material
The weldability of the various materials, as well as the recommended combinations of stud material and
parent material, depends on the process of stud welding. The combinations are shown in Tables A.3 and A.4.
Other combinations can be welded, but the weldability should be assured by welding procedure qualification.
Table A.3 — Weldability of typical combinations of stud and parent materials for drawn-arc stud
welding with ceramic ferrule or shielding gas and short-cycle drawn-arc stud welding
m
Parent material
ISO/TR 15608
material groups
2.2, 3 to 6
ISO/TR 15608
material groups 8
and 10
ISO/TR 15608
material groups 21
and 22
highly weldable for
any application a
weldable within
limits b
weldable within
limits b, c
not weldable
1.4762/X10CrAl24
weldable within
limits d
weldable within
limits d
weldable within
limits d
not weldable
1.4828/X15CrNiSi20
1.4841/X20CrNiSi25-4
weldable within
limits b
weldable within
limits b
weldable within
limits b
not weldable
weldable within
limits b
highly weldable for
any application a
not weldable
not weldable
not weldable
weldable within
limits b
S235
4.8 (weldable)
16Mo3
1.4742/X10CrAl18
1.4301/X5CrNi18-10
weldable within
limits b
1.4303/X5CrNi18-12
1.4401/X5CrNiMo17-12-2
1.4529/X1NiCrMoCuN25-20-7
/
bz
f
1.4541/X6CrNiTi18-10
xw
.c
o
ISO/TR 15608
material groups 1
and 2.1
Stud material
highly weldable for
any application a, e
1.4571/X5CrNiMoTi17-12-2
EN AW-AlMg3/EN AW-5754
EN AW-AlMg5/EN AW-5019
not weldable
For example, for force transfer.
b
For force transfer.
c
Only for short-cycle drawn-arc stud welding.
d
Only for heat transfer.
e
Up to 12 mm in diameter and shielding gas.
ww
w.
a
33
EN ISO 14555:2006
Table A.4 — Weldability of typical combinations of stud and parent materials for capacitor discharge
stud welding with tip ignition and for capacitor discharge drawn-arc stud welding
Parent material
S235
4.8 (weldable)
ISO/TR 15608 material
groups 1 to 6, 11.1 and
galvanized and metal
coated steel sheet, max.
thickness 25 µm of
coating
ISO/TR 15608
material
group 8
Copper and
lead free
copper alloys,
e.g. CuZn37
(CW508L)
ISO/TR 15608
material
groups 21
and 22
highly
weldable for
any
application a
weldable within limits b
highly
weldable for
any
application a
weldable within
limits b
not weldable
weldable within
limits b
not weldable
m
Stud material
ISO/TR 15608
material
groups 1 to 6,
11.1
weldable within limits b
highly
weldable for
any
application a
CuZn37 (no ISO
standard available)
weldable
within limits b
weldable within limits b
weldable
within limits b
highly weldable
for any
application a
not weldable
EN AW-Al99,5
not weldable
not weldable
not weldable
not weldable
weldable within
limits b
EN AW-AlMg3
not weldable
not weldable
not weldable
not weldable
highly weldable
for any
application a
1.4303
For example, for force transfer.
b
For force transfer.
bz
f
a
xw
.c
o
highly
weldable for
any
application a
1.4301
A.2.6 Weld assessment and recommended corrective actions
ww
w.
Weld assessment and recommended corrective actions are shown in Tables A.5, A.6, A.7 and A.8.
34
EN ISO 14555:2006
Table A.5 — Weld assessment and recommended corrective actions for drawn-arc stud welding with
ceramic ferrule or shielding gas
No.
Appearance
Assessment
Recommended corrective
actions
Visual examination
Collar regular, bright and complete. Acceptable (parameters are
correct).
Length after weld within tolerances.
2
Reduced diameter weld.
None.
3
Reduced, irregular and greyish
collar.
w.
Length too long.
Collar off centre with undercut.
ww
4
Insufficient protrusion (plunge) or lift. Increase protrusion (plunge) or lift.
Insufficient centering.
Check centering of ceramic ferrule.
Welding power too high.
Reduce current and/or welding
time.
Damping activity too strong.
Reduce damping activity.
bz
f
Length too long.
xw
.c
o
m
1
Weld energy too low.
Increase current and/or welding time.
Ceramic ferrule is moist.
Dry out ferrules in oven.
Lift too short.
Increase lift.
Effect of arc blow.
See Table A.8.
Ceramic ferrule incorrectly centred. Improve centring.
35
EN ISO 14555:2006
Table A.5 (continued)
No.
Appearance
Assessment
Recommended corrective
actions
Visual examination
Weld energy too high.
Collar height extremely reduced,
bright, with large lateral projections.
Plunge rate too high.
Length after weld too short.
Reduce current and/or welding time.
Adjust plunge and/or gun damper.
Fracture examination
Tearing of parent material.
7
Fracture above collar after
sufficient deformation.
8
Acceptable (parameters are
correct).
bz
f
6
xw
.c
o
m
5
None.
None.
Fracture within the weld.
Weld energy too low.
Increase current and/or welding time.
High porosity.
Unclean surface.
Clean the surface.
Material not suitable for stud
welding.
Select suitable material.
Carbon content of parent material
too high.
Select suitable material.
Cooling rate too high.
Increase welding time.
ww
w.
Acceptable (parameters are
correct).
9
Fracture in HAZ.
Greyish fracture surface without
sufficient deformation.
Preheating may be necessary.
36
EN ISO 14555:2006
Table A.5 (continued)
No.
Appearance
Assessment
Recommended corrective
actions
Fracture examination
Fracture of weld.
Flux content is too high.
Reduce flux quantity.
Bright appearance.
Welding time too low.
Increase welding time.
11
xw
.c
o
m
10
Lamellar tearing of parent material. Non metallic inclusions in parent
material.
Select suitable material.
ww
w.
bz
f
Parent material not suitable.
37
EN ISO 14555:2006
Table A.6 — Weld assessment and recommended corrective actions for short-cycle drawn-arc
stud welding
No.
Appearance
Assessment
Recommended corrective
actions
Visual examination
Regular collar, no visual defects.
Acceptable (parameters are
correct).
None.
2
Partial weld.
Weld energy too low.
Increase current and/or welding
time.
Polarity incorrect.
Correct polarity.
Welding time too long.
Reduce welding time.
Large irregular collar.
4
Pores in collar.
w.
ww
5
38
bz
f
3
xw
.c
o
m
1
Collar off centre with undercut.
Welding time too long.
Reduce welding time.
Current too low.
Increase current.
Oxidation of weld pool.
Provide suitable shielding gas.
Surface contaminated.
Clean the surface.
Effect of arc blow.
See Table A.8.
EN ISO 14555:2006
Table A.6 (continued)
No.
Appearance
Assessment
Recommended corrective
actions
Fracture examination
Tearing of parent material.
7
Fracture above collar after
sufficient deformation.
8
Fracture in HAZ.
Acceptable (parameters are
correct).
None.
xw
.c
o
m
6
Acceptable (parameters are
correct).
None.
Carbon content of parent material
too high.
Select suitable material.
Lack of penetration.
Heat input too low.
Increase heat input.
Incorrect weld polarity.
Correct weld polarity.
ww
w.
9
bz
f
Parent material not suitable.
39
EN ISO 14555:2006
Table A.7 — Weld assessment and recommended corrective actions for capacitor discharge
drawn-arc stud welding and capacitor discharge stud welding with tip ignition
No.
Appearance of fracture
Assessment
Recommended corrective
actions
Visual examination
1
Small weld spatter around joint.
None.
Considerable spatter around weld.
Weld spatter off centre with
undercut.
ww
4
40
Weld energy too low.
Increase weld energy.
Plunging speed too low.
Correct plunging speed.
Insufficient support of parent
material.
Provide support.
bz
f
3
Gap between flange and parent
material.
w.
2
xw
.c
o
m
No visual defects.
Acceptable (parameters are
correct).
Weld energy too high and/or
insufficient plunging speed.
Reduce weld energy.
Effect of arc blow.
See Table A.8.
Increase plunging speed.
EN ISO 14555:2006
Table A.7 (continued)
No.
Appearance
Assessment
Recommended corrective
actions
Fracture examination
Tearing of parent material.
6
Fracture of stud above flange.
7
Fracture in weld.
Acceptable (parameters are
correct).
None.
Acceptable (parameters are
correct).
None.
Weld energy too low.
Increase weld energy.
Plunging speed too low.
Increase plunging speed.
Combination stud/parent material
unsuitable.
Select suitable material.
bz
f
Deformation on reverse side.
Weld energy to high.
Reduce weld energy.
Pressure too high.
Reduce pressure.
Weld procedure not suitable.
Use gap weld procedure and not
contact weld procedure.
Parent material too thin.
Increase thickness of parent
material.
ww
w.
8
xw
.c
o
m
5
41
EN ISO 14555:2006
Table A.8 — Effect of arc blow and some possible remedies
No.
Cause
Remedy
xw
.c
o
m
A
ww
w.
bz
f
B
C
NOTE
Arc blow is proportional to current intensity and can be influenced by symmetrically attaching mass clamps and
compensating masses, or (in the case of hand guns with an external welding cable) by turning the gun around the vertical axis. Arc blow
generates one-sided melting and can increase the number of pores in the welded materials, but it can be reduced by suitable
application of different remedies.
42
EN ISO 14555:2006
A.2.7 Drawn arc stud welding with ceramic ferrule or shielding gas and short-cycle
drawn-arc stud welding
A.2.7.1
A.2.7.1.1
Welding equipment
General
The welding equipment consists of the power source, control unit, movable fixture and welding cables.
A.2.7.1.2
Power sources
xw
.c
o
m
Power sources are either rectifiers or converters which supply direct current and are suitable for brief, high
loads. The maximum current intensity in the case of the largest standard studs is approximately 2 500 A. The
duty cycle is 3 % to 10 %. This means that even for high currents, systems are relatively light and compact.
The open circuit voltage is between 70 V and 100 V and should conform to IEC 60974-1.
NOTE
It is intended that the current intensity be continuously adjustable over the entire range. Systems incorporating
constant current control are particularly advantageous.
A.2.7.1.3
Control unit
Control units switch the welding current in accordance with the desired welding time. They also control the
movement of the gun. The power source and control unit are combined in most systems (compact systems).
A.2.7.1.4
Movable fixtures
bz
f
Movable fixtures are either hand-held guns or welding heads. Welding heads are preferable for automatic stud
feed and are securely connected to a frame.
The movable fixture incorporates the following:
a)
the drive, to lift the stud for arc starting and to keep the lift at a constant length during the arc time, with
respect to the support fixture;
NOTE 1
In most cases, the drive is electromagnetic.
w.
b) a spring, to plunge the stud into the molten pool after the end of the welding period;
c) on some guns, a hydraulic or pneumatic damper, to reduce the plunge speed;
In particular, a damper is incorporated when stud diameters are in excess of 14 mm.
ww
NOTE 2
d) a clamping fixture, to hold the stud in the welding position and to transfer the current to the stud;
e) a support fixture, to absorb the reaction force of the press-on force;
NOTE 3
In the case of hand guns, the support fixture can centre the ceramic ferrule or allow the stud to be positioned
on the work piece (e.g. by way of stops or templates). The support can be made either directly mechanically, or by means
of electronic control.
f)
in the case of welding heads for automatic feed, a feed chamber and a positioning unit for the stud.
NOTE 4
In most cases, the positioning unit is pneumatic.
Changing clamping fixtures, and sometimes parts, of the support fixture enables a movable fixture to be used
for different stud dimensions.
The movable fixture is a power tool. The appropriate safety regulations should therefore be observed in order
to avoid hazards connected with electrical voltage, heating and arc formation.
43
EN ISO 14555:2006
A.2.7.1.5
Welding cables
The welding cables shall conform to ISO 5828 and shall be dimensioned so that impermissible heating is
avoided. 50 mm2 is recommended for studs with a diameter of up to 12 mm. Cross-sections of at least
70 mm2 are recommended for studs of up to 20 mm diameter. Cross-sections of 120 mm2 are recommended
for larger studs. The cable and, in particular, all connection points should be checked regularly for damage.
Damaged system components shall be replaced.
NOTE
Depending on the type of power source and the length of the welding cable, the cross-section of the welding
cables is increased.
A.2.7.2.1
Welding parameters
m
A.2.7.2
Polarity
A.2.7.2.2
Welding current
xw
.c
o
When welding steel, the stud is connected to the negative pole and the work piece is connected to the positive
pole. Opposite polarity has proven successful for special metals, e.g. aluminium and its alloys, and brass.
Depending on the stud dimensions, the welding current is between approximately 300 A and 3000 A. For
drawn-arc stud welding with ceramic ferrule or shielding gas of unalloyed steel, the correct current can be
estimated on the basis of Equations (A.1) and (A.2):
I (A) = 80 × d (mm) — for studs up to approximately 16 mm diameter
(A.1)
I (A) = 90 × d (mm) — for studs of over 16 mm diameter
(A.2)
bz
f
Normally, a current approximately 10 % less is selected for stainless steel.
A current as high as possible (600 A to 1 800 A, depending on the size of the power source) is set for
short-cycle drawn-arc stud welding.
A.2.7.2.3
Arc voltage
A.2.7.2.4
w.
The arc voltage is mainly determined by the lifting height and the welding current. Values of between 20 V and
40 V are the norm. Surface impurities, such as oil or grease, increase the arc voltage compared with the
normal state, whilst inert gases reduce it.
Welding time
ww
For drawn-arc stud welding with ceramic ferrule or shielding gas, the welding time can be estimated on the
basis of Equations (A.3) and (A.4):
tw (s) = 0,02 × d (mm) — for studs of up to approximately 12 mm diameter
(A.3)
tw (s) = 0,04 × d (mm) — for studs over 12 mm diameter
(A.4)
The given values apply to weldings in the welding position PA. The welding time shall be reduced for welding
in the welding position PC, in accordance with ISO 6947.
In the case of short cycle stud welding, the welding time is less than 100 ms. It depends not only on the stud
diameter, but also on the available current intensity. The welding time should be as short as possible in the
case of welding without weld pool protection.
44
EN ISO 14555:2006
A.2.7.2.5
Lift
The lift is between approximately 1,5 mm and 8 mm and is proportional to the stud diameter. In the case of
coated surfaces (e.g. through-deck-welding technique), the lift shall be greater than normal. Greater lift
increases the arc length and therefore the arc voltage. The magnetic deflection of the arc also increases (arc
blow).
A.2.7.2.6
Protrusion
A.2.7.2.7
m
Generally, the protrusion is 1 mm to 8 mm and proportional to the stud diameter. It also depends on the
desired shape of the weld collar, the shape of the stud base and (when welding with a ceramic ferrule) the
collar area of the ferrule.
Plunging speed
xw
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The plunging speed should be approximately 200 mm/s for studs with a diameter of up to 14 mm diameter
and 100 mm/s for larger studs, so as to prevent the weld pool splashing. It is proportional to the protrusion in
the case of movable fixtures without dampers.
A.2.8 Capacitor discharge drawn-arc stud welding and capacitor discharge stud welding
with tip ignition
A.2.8.1
A.2.8.1.1
Welding equipment
General
A.2.8.1.2
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The welding equipment consists of the power source, incorporating a charging unit, the movable fixture and
the welding cable.
Power source
w.
The power source incorporates a capacitor bank with capacitances of between approximately 12 mF and
150 mF. The capacitance is sometimes adjustable in steps. The charging voltages are up to approximately
200 V and require a safety switch-off facility conforming to IEC 60974-1. In most cases, the charging voltages
are continuously adjustable.
Drawn arc capacitor discharge power sources have an additional coil in the welding circuit to provide a
welding time of 6 ms to 10 ms.
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The capacitor bank shall be charged to the desired voltage before every welding operation. The maximum
welding sequence depends on the charging speed. Approximately 500 studs per hour can be welded with
manual-operated power sources, and up to 3 500 studs per hour can be welded in automatic mode.
A.2.8.1.3
Movable fixture
The movable fixtures are either hand guns or welding heads. Welding heads are preferable for automatic stud
feed and are securely connected to a frame. In the drawn-arc method, the arc is created by lifting the stud. In
the tip ignition method, the electromagnetic drive creates a gap between stud material and parent material.
The arc is ignited by contact of the tip to the work piece. The design of the movable fixture depends on
whether the method used for starting the arc is the drawn-arc or capacitor discharge method. The movable
fixture incorporates the following:
a)
the drive, to lift the stud and to keep the lift at a constant length during the arc time, with respect to the
support fixture;
NOTE 1
In most cases, the drive is electromagnetic.
45
EN ISO 14555:2006
b) a spring, to plunge the stud into the molten pool after the end of the welding period;
c) a clamping fixture, to hold the stud in the welding position and to transfer the current to the stud;
d) a support fixture, to absorb the reaction force of the press-on force;
NOTE 2
In the case of hand guns, the support fixture allows the stud to be positioned on the work piece, (e.g. by way
of stops or templates). The support can be made either directly mechanically, or by means of electronic control.
e) in the case of welding heads for automatic feed, a feed chamber and a positioning unit for the stud.
NOTE 3
In most cases, the positioning unit is pneumatic.
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An electromagnetic drive is not absolutely essential in the case of movable fixtures operating with stud
welding with tip ignition. Springs tensioned by hand can also be used to create the necessary arc gap.
Changing clamping fixtures enables a movable fixture to be used for different stud dimensions.
The movable fixture is a power tool. The appropriate safety regulations should therefore be observed in order
to avoid hazards connected with electrical voltage, heating and arc formation.
A.2.8.1.4
Welding cables
Welding cables should be used in accordance with ISO 5828.
A.2.8.2
A.2.8.2.1
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The cross-sections of the welding cables are generally 25 mm 2 to 70 mm2. They should be as short as
possible, due to the high peak currents and the associated voltage drop. Winding the welding cable into coils
increases the inductive resistance, which in turn reduces the welding current, but the welding time is
increased.
Welding parameters
Polarity
A.2.8.2.2
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In general, the stud is connected to the negative pole and the work piece is connected to the positive pole.
Reverse polarity can be advantageous for copper and aluminium alloys.
Welding current
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The peak current is between 1 000 A and 10 000 A and depends on the charging voltage, the capacitance
and the inductive and ohmic resistance of the welding cable.
A.2.8.2.3
Welding time
The welding time cannot be selected directly. Depending on the stored energy and the inductance of the
welding circuit, it is 1 ms to 3 ms (tip ignition), or 3 ms to 10 ms (drawn-arc). A longer welding time simplifies
welding on a coated surface, by virtue of better degassing.
A.2.8.2.4
Charging energy
Together with the capacitance, the charging voltage determines the charging energy on the basis of
Equation (A.5):
W = 0,5 × C × U 2
The charging energy shall be increased with the weld cross-section.
46
(A.5)
EN ISO 14555:2006
A.2.8.2.5
Plunging speed
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The plunging speed is in general determined by a spring and the mass of the moving parts. With some
movable fixtures, the spring force can be changed by the operator. The plunging speed is approximately
0,5 m/s to 1,5 m/s (sometimes more). In the case of the tip ignition method, it directly determines the welding
time, in conjunction with the stud tip length. It is therefore necessary to maintain the plunging speed within
limits at all times, in order to obtain a constant quality.
47
EN ISO 14555:2006
Annex B
(normative)
Quality requirements for stud welding
Table B.1 — Quality requirements for stud welding
Comprehensive quality
requirements in
accordance with
ISO 3834-2
Standard quality
requirements in
accordance with
ISO 3834-3
Elementary quality
requirements in
accordance with
ISO 3834-4
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Quality requirements in
ISO 3834-2, ISO 3834-3 or
ISO 3834-4 required for stud
welding
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Table B.1 shows quality requirements for stud welding.
Structures subjected to
fatigue loading
Technical knowledge of
welding coordination
personnel
Basic knowledge in accordance with 6.2
6.2 does not apply
Quality record
Production surveillance record in accordance with 14.6
14.6 does not apply
Method of qualification of
pWPS
Welding procedure test in accordance with 10.2 or
pre-production test in accordance with 10.3
Previous experience in
accordance with 10.4
Calibration of measurement
and testing equipment
Procedures shall be
available in accordance with 14.8 does not apply
14.8
Production test in accordance with 14.2; simplified
production test in accordance with 14.3; production
surveillance in accordance with 14.5
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Process control
48
Structures subjected to
specified static loading
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Fields of application unless
otherwise specified
Structures subjected to
unspecified static loading
Simplified production test in
accordance with 14.3,
production surveillance in
accordance with 14.5
EN ISO 14555:2006
Annex C
(informative)
Manufacturer's welding procedure specification (WPS)
Welding current
A
m
Control unit:
Welding position:
Welding time
Protrusion
Lift
s
mm
mm
Remarks
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Drawn arc stud
welding with
ceramic ferrule or
shielding gas and
short-cycle
drawn-arc stud
welding
Examiner or Examining body
Reference No.:
Stud-welding process:
Method of cleaning or
surface condition of parent material:
Stud material:
Stud designation:
Stud diameter (mm):
no
Use of damper:
yes
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Manufacturer's welding procedure
Reference No.:
Manufacturer:
WPQR No.:
Parent material:
Parent material thickness (mm):
Preheat temperature (°C):
Shielding gas and flow rate:
Ceramic ferrule designation:
Redrying of ceramic ferrule: ......... h ........... °C
Power source:
Welding gun/head:
Gap
Charging voltage
Capacitance
Spring force
mm
V
mF
N
Remarks
or plunging speed
mm/s
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Capacitor discharge stud
welding with tip ignition and
capacitor discharge
drawn-arc stud welding
Additional remarks: ...............................................................................................................................................
...............................................................................................................................................................................
...............................................................................................................................................................................
Manufacturer:
Examiner or Examining body:
(Name, date and signature):
(Name, date and signature):
49
EN ISO 14555:2006
Annex D
(informative)
Welding procedure qualification record form (WPQR) (for drawn-arc
stud welding with ceramic ferrule or shielding gas and short-cycle
drawn-arc stud welding)
Welding procedure qualification — Test certificate
Examiner or Examining body:
Code/testing standard:
m
Manufacturer:
Address:
Manufacturer's welding procedure
Reference No.:
Extent of qualification
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Date of welding:
Name of operator:
Stud-welding process:
Stud material:
Stud diameter (mm):
Stud length (mm):
Parent material:
Parent material thickness (mm):
Stud designation:
Application u 100 °C
Ceramic ferrule designation:
Use of damper:
Redrying of ceramic ferrule: ......... h .........°C
Welding position:
no
Power source:
Welding gun/head:
Control unit:
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Preheat temperature (°C)
Shielding gas and flow rate:
yes
Application > 100 °C
Other information: ..................................................................................................................................................
................................................................................................................................................................................
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................................................................................................................................................................................
Welding time
Protrusion
Lift
A
s
mm
mm
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Welding current
Remarks
Certified that test welds are prepared, welded and tested satisfactorily, in accordance with the requirements of
the code/testing standard indicated above.
Location:
Date of issue:
Examiner or Examining body:
................................................................................................................................................................................
(Name, date and signature)
50
EN ISO 14555:2006
Manufacturer's welding procedure
Examiner or Examining body
Reference No.:
Reference No.:
Application > 100 °C
Application u 100 °C
Abbreviations:
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no
a
na
no objections
acceptable
not acceptable
NOTE
Numbers 100 and 400 refer to ISO 6520-1.
1)
Visual examination
Remarks: ..................................................
..................................................................
..................................................................
2)
Bend testing
Assessment: .................................................................................
.......................................................................................................
.......................................................................................................
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..................................................................
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uc
unequal collar
ic
incomplete collar
201-2 × 3 2 pores of 3 mm diameter (example)
nf
no fracture
wf
fracture in weld
sf
fracture in stud
100
crack
400
lack of fusion
.......................................................................................................
Bend testing (application u 100 °C) / bend testing by means of torque wrench (application > 100 °C)
Bending angle/
bending moment
Nm
Location of
fracture
Remarks
Assessment
ww
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Specimen number
51
EN ISO 14555:2006
Tensile testing (only for application u 100 °C)
3)
Specimen
number
Fracture
load
Location
of fracture
Fracture
strength
Size of
imperfection
area
Size of the
largest
imperfection
N/mm2
mm2
mm
Radiographic examination (only for application u 100 °C, d > 12 mm)
Type of
imperfections
Size of imperfection
area
Size of the largest
imperfection
mm2
mm
Remarks
Assessment
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Specimen number
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4)
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N
Remarks Assessment
5)
Macro examination
Specimen
number:
Picture
52
Picture
number:
Magnification:
Result
Assessment
Specimen
number:
Picture
Picture
number:
Magnification:
Result
Assessment
EN ISO 14555:2006
6)
Torque test (only for short cycle drawn-arc stud welding)
Torque
Nm
Location of fracture
Remarks
Assessment
7)
Additional tests
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Specimen number
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Remarks and additional steps: .............................................................................................................................
...............................................................................................................................................................................
...............................................................................................................................................................................
Test carried out in accordance with the requirements of: .....................................................................................
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...............................................................................................................................................................................
Laboratory Report Reference No.: ........................................................................................................................
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Test results are acceptable/not acceptable (delete as appropriate)
Examiner or Examining body:
Test carried out in the presence of: ......................................................................................................................
(Name, date and signature)
53
EN ISO 14555:2006
Annex E
(informative)
Welding procedure qualification record form (WPQR) (for capacitor
discharge stud welding with tip ignition and capacitor discharge
drawn-arc stud welding)
Manufacturer:
Address:
Examiner or Examining body:
Code/testing standard:
Manufacturer's welding procedure
Reference No.:
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Date of welding:
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Welding procedure qualification — Test certificate
Name of operator:
Extent of qualification
Stud-welding process:
Stud diameter (mm):
Stud material:
Parent material:
Stud length (mm):
Stud designation:
Parent material thickness (mm):
Welding:
with gap
with contact
Power source:
Welding gun/head:
bz
f
Shielding gas and flow rate:
Other information: ..................................................................................................................................................
................................................................................................................................................................................
................................................................................................................................................................................
Charging voltage
Gap
Spring force
mF
V
mm
N
Remarks
or plunging speed
mm/s
ww
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Capacitance
Certified that test welds are prepared, welded and tested satisfactorily, in accordance with the requirements of
the code/testing standard indicated above.
Location:
Date of issue:
Examiner or Examining body:
................................................................................................................................................................................
(Name, date and signature)
54
EN ISO 14555:2006
Manufacturer's welding procedure
Examiner or Examining body
Reference No.:
Reference No.:
Application > 100 °C
Application u 100 °C
unequal spatters
incomplete spatter ring
no fracture
fracture in weld
fracture in stud
non-welded fracture area in % (e.g. 10 %)
crack
lack of fusion
no
a
na
no objections
acceptable
not acceptable
NOTE
Numbers 100 and 400 refer to ISO 6520-1.
1)
Visual examination
Remarks: ..................................................
Assessment: .................................................................................
.......................................................................................................
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..................................................................
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is
nf
wf
sf
400-10
100
400
m
Abbreviations:
..................................................................
.......................................................................................................
..................................................................
.......................................................................................................
2)
Bend testing
Bending angle
Location of fracture
Remarks
Assessment
ww
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Specimen number
55
EN ISO 14555:2006
3)
Tensile testing
Specimen
number
Fracture
load
Location of
fracture
Size of
imperfection
area
Size of the
largest
imperfection
N/mm2
mm2
mm
Remarks
Assessment
4)
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N
Fracture
strength
Additional tests
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Remarks and additional steps: ..............................................................................................................................
................................................................................................................................................................................
................................................................................................................................................................................
Test carried out in accordance with the requirements of: .....................................................................................
................................................................................................................................................................................
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Laboratory Report Reference No.: ........................................................................................................................
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Test results are acceptable/not acceptable (delete as appropriate)
Examiner or Examining body:
Test carried out in the presence of: .......................................................................................................................
56
(Name, date and signature)
EN ISO 14555:2006
Annex F
(informative)
Test results — Production test (for drawn-arc stud welding with ceramic
ferrule or shielding gas and short-cycle drawn-arc stud welding)
Welding procedure specification
Reference No.:
Welding process:
Project number:
Location of welding:
Shop/on site:
Parent material:
Parent material thickness (mm):
Stud material:
Stud diameter (mm):
Stud designation:
Operator:
Date of test welding:
Welding current
Welding time
Protrusion
Lift
A
s
mm
mm
Remarks
bz
f
Drawn arc stud welding with ceramic
ferrule or shielding gas and short-cycle
drawn-arc stud welding
Abbreviations:
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Drawing No.:
Position No.:
m
Manufacturer's welding procedure
Reference No.:
w.
uc
unequal collar
ic
incomplete collar
201-2 × 3 2 pores of 3 mm diameter (example)
nf
no fracture
wf
fracture in weld
sf
fracture in stud
100
crack
400
lack of fusion
no objections
acceptable
not acceptable
ww
no
a
na
NOTE
1)
Numbers 100 and 400 refer to ISO 6520-1.
Visual examination
Remarks: ..................................................
Assessment: ..................................................................................
..................................................................
.......................................................................................................
..................................................................
.......................................................................................................
57
EN ISO 14555:2006
2)
Bend testing
Bend testing (application u 100 °C) / bend testing by means of torque wrench (application > 100 °C)
Bending angle/
bending moment
Location of fracture
Magnification:
Assessment
Remarks
Assessment
3)
Macro examination
Specimen
number:
Picture
number:
Result
4)
Specimen
number:
Picture
number:
Magnification:
Result
Assessment
Picture
Additional tests
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Picture
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Specimen number
Total assessment: .................................................................................................................................................
................................................................................................................................................................................
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................................................................................................................................................................................
Remarks and additional steps: ..............................................................................................................................
................................................................................................................................................................................
................................................................................................................................................................................
ww
................................................................................................................................................................................
Test carried out in the presence of: .......................................................................................................................
................................................................................................................................................................................
................................................................................................................................................................................
................................................................................................................................................................................
Welding coordinator: ....................................................
Examiner or Examining body: ..................................
.......................................................................................
...................................................................................
Locality: ........................................................................
Date: .........................................................................
.......................................................................................
(Signature of welding coordinator)
...................................................................................
(Signature of examining body)
58
EN ISO 14555:2006
Annex G
(informative)
Test results — Production test (for capacitor discharge stud welding
with tip ignition and capacitor discharge drawn-arc stud welding)
Welding procedure specification
Reference No.:
Welding process:
Project number:
Location of welding:
Shop/on site:
Parent material:
Parent material thickness (mm):
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Drawing No.:
Position No.:
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Manufacturer's welding procedure
Reference No.:
Stud material:
Stud diameter (mm):
Stud designation:
Operator:
Date of test welding:
Capacitor discharge stud welding
with tip ignition and capacitor
discharge drawn-arc stud welding
Capacitance
Charging voltage
Gap
Spring force
mF
V
mm
N
Remarks
Abbreviations:
bz
f
or plunging speed
unequal spatters
incomplete spatter ring
no fracture
fracture in weld
fracture in stud
non-welded fracture area in % (e.g. 10 %)
crack
lack of fusion
no
a
na
no objections
acceptable
not acceptable
NOTE
Numbers 100 and 400 refer to ISO 6520-1.
ww
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us
is
nf
wf
sf
400-10
100
400
mm/s
1)
Visual examination
Remarks: ..................................................
Assessment: ..................................................................................
..................................................................
.......................................................................................................
..................................................................
.......................................................................................................
..................................................................
.......................................................................................................
59
EN ISO 14555:2006
2)
Bend testing
Bending angle
Location of fracture
Remarks
Assessment
Tensile testing
Specimen
number
Fracture
load
Location of
fracture
N
4)
Additional tests
Fracture
strength
N/mm2
Size of
imperfection
area
Size of the
largest
imperfection
mm2
mm
Remarks
Assessment
bz
f
3)
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Specimen number
Total assessment: .................................................................................................................................................
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................................................................................................................................................................................
................................................................................................................................................................................
Remarks and additional steps: ..............................................................................................................................
................................................................................................................................................................................
ww
................................................................................................................................................................................
................................................................................................................................................................................
Test carried out in the presence of: .......................................................................................................................
................................................................................................................................................................................
................................................................................................................................................................................
Welding coordinator: .....................................................
Examiner or Examining body: ..................................
........................................................................................
...................................................................................
Locality: .........................................................................
Date: .........................................................................
........................................................................................
Signature of welding coordinator
...................................................................................
Signature of examining body
60
EN ISO 14555:2006
Annex H
(informative)
Example for production surveillance record
Number of
welds
tested
WPS
number
Project
number/
drawing
number/
position
number
Stud
diameter/
length
mm
Time of
test
welding
Number
of studs
Result of
visual
examination
m
Shift
number
ww
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bz
f
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Date of
welding
61
EN ISO 14555:2006
Bibliography
ISO 3834-5, Quality requirements for fusion welding of metallic materials — Part 5: Documents with
which it is necessary to conform to claim conformity to the quality requirements of ISO 3834-2,
ISO 3834-3 or ISO 3834-4
[2]
ISO 5828, Resistance welding equipment — Secondary connecting cables with terminals connected to
water-cooled lugs — Dimensions and characteristics
[3]
ISO 6520-1, Welding and allied processes — Classification of geometric imperfections in metallic
materials — Part 1: Fusion welding
[4]
ISO/TR 20172, Welding — Grouping systems for materials — European materials
[5]
ISO/TR 20173, Welding — Grouping systems for materials — American materials
[6]
ISO/TR 20174, Welding — Grouping systems for materials — Japanese materials
[7]
IEC 60974-1, Arc welding equipment — Part 1: Welding power sources
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[1]
62
blank
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BS EN ISO
14555:2006
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